Improved Meet-in-the-middle Attacks on Reduced-roundMIBS-80 Cipher br

MIBS is a Feistel structured lightweight block cipher aimed at extremely constrained resourcesenvironment. In this paper, an 8-round meet-in-the-middle distinguisher of MIBS is constructed by utilizingmultiset and effective differential enumeration technique. Then, the meet-in-the-middle attacks on 12-round and13-round MIBS-80 are proposed based on the new distinguisher. In the attack process, the plaintexts arefiltered utilizing the differential properties and the guessed keys are reduced using the relation of master keyand round key in the key expansion algorithm of MIBS-80. The time complexity of attacking 12-round and 13-round MIBS-80 is 253.2 and 262?respectively. Compared with the known results of the meet-in-the-middleattack, the number of rounds of meet-in-the-middle attack on MIBS-80 is increased by 2-round